The present invention relates to a dental coating composition comprising a polymer which has in its molecule one or more phosphorus series acid residues selected from the group consisting of phosphoric acid, phosphonic acid and phosphinic acid and halides and salts thereof and has a weight-average molecular weight of 10,000 to 5,000,000, and water or a lower alcohol. The composition is a dental coating agent which does not easily peel off when drinking or eating, can be removed easily if necessary and does not have a safety problem.